Plasma etchers utilize directed ribbon ion beams to achieve complex etching and surface processing, thus solving many challenges in the fabrication of most advanced 3D semiconductor structures. Characterization of the ion beam, monitoring process end-points, and advanced plasma probing are relevant metrologies necessary for implanter operations. Currently, the metrologies are achieved with different mechanisms, such as Faraday cup arrays and free space optical emission spectrum (OES). These approaches have their limits and disadvantages. For example, the Faraday cup array is an in-chamber metrology device. As a result, the Faraday cup array presentation brings in extra particles and metals. Furthermore, patch charges accumulated on the shield of the Faraday cup array may also perturb the beam path and give results deviating from the actual values. The free space OES is widely adopted in process endpoint control, yet cannot resolve the ion beam's spatial distribution, and may suffer from various optical noises from the environment and from different materials in the etching beam.
The present disclosure addresses at least the above identified deficiencies of the prior art.